During World War I, and for several years after, a National Bureau of Standards (NBS) team under Harvey L. Curtis developed both apparatus and methods for measuring the characteristics of large naval guns, including muzzle velocity, time of firing and ejection, and motion of the projectile in the bore. Studies involved experimental firings undertaken jointly by NBS and the Naval Research Laboratory with the cooperation of the Naval Proving Ground at Dahlgren, Virginia. One of these studies involved the determination of the displacement of the projective inside the gun. The method adopted by NBS to determine this displacement was based on the fact that as the projectile moves through the bore of the gun, the sudden increase in pressure on a section that the projectile just passed, is accompanied by a radial expansion of the gun at that section. To obtain a time record of this expansion at a number of points along the gun, expansometers were clamped along the barrel of a gun by slender steel straps encircling the barrel. As the projectile passed inside, the barrel bulged and separated contact points, thus breaking the electric circuit of each expansometer and, in turn, causing sequenced timing signals on an oscillograph. The function of the expansometer was to detect the expansion and record the time at which it occurred rather than, as the name implies, to measure it.

Publications

'The Correlation of Diverse Ballistic Records: A Report of the Experimental Firing of a 14� � 50 Caliber Gun No. 89-L2 at Naval Proving Ground Dahlgren Virginia, October 26-30, 1923,' Reported to Bureau of Ordnance, Navy Department, April 1924, by the National Bureau of Standards, in Very complete ballistic data on a 14-inch gun and two attempts at its analysis: observations made at Dahlgren Proving Ground by personnel of National Bureau of Standards in 1923 by Harvey Lincoln Curtis, H.C. Richards, and C. Snow (Washington DC: National Bureau of Standards, 1924).

Object Dimensions

[H] 7 cm [W] 8 cm [L] 18 cm

Rights

Use of the images from the NIST Digital Archives is not restricted, but a statement of attribution is required. Please use the following attribution statement: "National Institute of Standards and Technology Digital Collections, Gaithersburg, MD 20899"